Re: [PATCH] xfs: get rid of xfs_ag_resv_rmapbt_alloc

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Jul 02, 2024 at 09:48:51PM +0800, Long Li wrote:
> The pag in xfs_ag_resv_rmapbt_alloc() is already held when the struct
> xfs_btree_cur is initialized in xfs_rmapbt_init_cursor(), so there is no
> need to get pag again.
> 
> On the other hand, in xfs_rmapbt_free_block(), the similar function
> xfs_ag_resv_rmapbt_free() was removed in commit 92a005448f6f ("xfs: get
> rid of unnecessary xfs_perag_{get,put} pairs"), xfs_ag_resv_rmapbt_alloc()
> was left because scrub used it, but now scrub has removed it. Therefore,
> we could get rid of xfs_ag_resv_rmapbt_alloc() just like the rmap free
> block, make the code cleaner.
> 
> Signed-off-by: Long Li <leo.lilong@huawei.com>
> ---
>  fs/xfs/libxfs/xfs_ag_resv.h    | 19 -------------------
>  fs/xfs/libxfs/xfs_rmap_btree.c |  8 +++++++-
>  2 files changed, 7 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_ag_resv.h b/fs/xfs/libxfs/xfs_ag_resv.h
> index ff20ed93de77..f247eeff7358 100644
> --- a/fs/xfs/libxfs/xfs_ag_resv.h
> +++ b/fs/xfs/libxfs/xfs_ag_resv.h
> @@ -33,23 +33,4 @@ xfs_perag_resv(
>  	}
>  }
>  
> -/*
> - * RMAPBT reservation accounting wrappers. Since rmapbt blocks are sourced from
> - * the AGFL, they are allocated one at a time and the reservation updates don't
> - * require a transaction.
> - */
> -static inline void
> -xfs_ag_resv_rmapbt_alloc(
> -	struct xfs_mount	*mp,
> -	xfs_agnumber_t		agno)
> -{
> -	struct xfs_alloc_arg	args = { NULL };
> -	struct xfs_perag	*pag;
> -
> -	args.len = 1;
> -	pag = xfs_perag_get(mp, agno);
> -	xfs_ag_resv_alloc_extent(pag, XFS_AG_RESV_RMAPBT, &args);
> -	xfs_perag_put(pag);
> -}
> -
>  #endif	/* __XFS_AG_RESV_H__ */
> diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
> index 9e759efa81cc..aa1d29814b74 100644
> --- a/fs/xfs/libxfs/xfs_rmap_btree.c
> +++ b/fs/xfs/libxfs/xfs_rmap_btree.c
> @@ -88,6 +88,7 @@ xfs_rmapbt_alloc_block(
>  	struct xfs_buf		*agbp = cur->bc_ag.agbp;
>  	struct xfs_agf		*agf = agbp->b_addr;
>  	struct xfs_perag	*pag = cur->bc_ag.pag;
> +	struct xfs_alloc_arg    args = { NULL };

You could make this even more compact with

	struct xfs_alloc_arg	args = { .len = 1 };

Otherwise this looks ok to me as a cleanup.

--D

>  	int			error;
>  	xfs_agblock_t		bno;
>  
> @@ -107,7 +108,12 @@ xfs_rmapbt_alloc_block(
>  	be32_add_cpu(&agf->agf_rmap_blocks, 1);
>  	xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
>  
> -	xfs_ag_resv_rmapbt_alloc(cur->bc_mp, pag->pag_agno);
> +	/*
> +	 * Since rmapbt blocks are sourced from the AGFL, they are allocated one
> +	 * at a time and the reservation updates don't require a transaction.
> +	 */
> +	args.len = 1;
> +	xfs_ag_resv_alloc_extent(pag, XFS_AG_RESV_RMAPBT, &args);
>  
>  	*stat = 1;
>  	return 0;
> -- 
> 2.39.2
> 
>